In the following Patent Document 1, a detachable insert type cutting tool is disclosed which is used for grooving work of an end face. In this cutting tool, as shown in FIG. 15, an upper jaw section 102 and a lower jaw section 103 which pinch and fix a cutting insert 100 from the upper and lower directions are provided in a head member main body 101 on which the cutting insert 100 is detachably mounted. An insert mounting seat 104 for cutting insert mounting is provided between the lower surface of the upper jaw section 102 and the upper surface of the lower jaw section 103 which face each other. Curved convex curve outer surfaces 105 are formed on one side of the upper and lower jaw sections 102 and 103 when viewed from the leading end sides of the upper and lower jaw sections 102 and 103, and curved concave curve inner surfaces 106 are formed on the other side of the upper and lower jaw sections 102 and 103, whereby the upper jaw section 102 and the lower jaw section 103 are formed in arch shapes when viewed from the leading end sides.
In addition, in FIG. 15, Xa denotes a locus of a work material which passes an inner corner portion 100a of a cutting edge of the cutting insert 100, Xb denotes a locus of the work material which passes an outer corner portion 100b of the cutting edge of the cutting insert 100, and an area between the loci Xa and Xb is subjected to grooving work. Further, Oa denotes the rotation center of the work material.